The Marrying Kind
by skygirl55
Summary: Many years earlier, childhood best friends Rick and Kate made a marriage pact. Now, while playing a silly quiz game, the topic resurfaces. AU. One Shot.
_A/N: This was inspired by a Tumblr reblog i did a few days ago basically invovling a bunch of AU scenarios where a male/female couple is just friends. The one that stuck out to me was a mention of a marriage pact. This is the result - its semi-AU from canon_

* * *

"Oh! I nearly forgot! I found the perfect thing for you guys!" Jenny slid the duffle bag resting on the sand beside her chair over so it lay atop her feet before unzipping it and pulling out spare diapers, a blanket, a pacifier, and then finally her iPad.

Esposito clicked his tongue. "This isn't another thing from your mommy blogs, is it? Because I think I've heard enough about diaper rash to last a lifetime."

Jenny gave him a look. "I didn't mean _you_ Javi—them," she said, gesturing towards the duo across from her.

Lying on her stomach on a blanket, her legs protruding out from the shadow of their two beach umbrellas, Kate Beckett was oblivious until the man sitting in a lounge chair beside her tapped her on the shoulder.

"You awake, Kate?"

"Hmm? Yes I'm listening…" she said, though her tone was sluggish and indicated she may have been near sleep.

"Well c'mere I want to show you something." Jenny informed her.

Grumbling slightly, Kate pushed herself up into a kneeling position and adjusted the top of her bikini. Before sitting back on her heels she reached out and took the red shirt featuring The Flash's logo draped over the back of the man's chair. He glanced over at her casually as she pulled it over her head. "Forget your cover-up again?"

"'s back at the house; don't feel like getting it."

"Here," Jenny said, standing out of her chair so she could pass the iPad over to the man who had given it to her and her husband as a gift the previous Christmas.

Richard Castle accepted the device and held it on his right side so the woman beside him could also read the screen. While he was still gazing over the display, she scoffed.

"'Quiz: Should You Marry Your Best Friend?'" She read the title and then without any thought said, "We're not doing this."

Jenny laughed, having expected that reaction from her no-nonsense friend. "Yeah, c'mon. It'll be fun."

As Kate grumbled, "Fun for whom?" under her breath, Jenny's husband Kevin Ryan returned from taking their five-month-old down to see the water. "What'll be fun?" he asked, passing the little girl over to her mother and taking a seat on the blanket beside her.

"I'm trying to get Rick and Kate to take that quiz I showed you."

After taking a swig of his beer, Kevin nodded. "Oh yeah, that'll definitely be funny."

Kate shot her coworker a look, which he ignored, and she fought the urge to pout. All four of them had known her for years and thus knew about her aversion to revealing personal details outside of very specific circumstances. Quizzes from ridiculous online websites fell about twelve miles outside those circumstances. All she wanted to do was enjoy her Memorial Day weekend at her best friend's Hamptons Beach house like they had done every year since its purchase seven years earlier. Prior to their arrival Kate hoped year would be even more fun because of the baby and so far she had been right though it appeared those sentiments were about to change rapidly.

"C'mon, Kate." Rick nudged her with his elbow. "Where's the harm? You're not scared it'll say yes, are you?" he asked, waggling his eyebrows.

Kate rolled her eyes. Of course the writer was her best friend and had been for the duration of their adult lives. No quiz on the internet would be able to discern whether or not their relationship should progress to another level; such a notion was silly. However, the grin on Rick's face told her he _was_ interested, which means she had no choice but to partake. "Fine." She sighed out and shifted so she sat on her left hip, her left hand against the blanket to brace her position. They may as well get this over with; hopefully there would only be a few questions.

"Great! We'll do it together!" After passing their daughter to her husband, Jenny reached out for the iPad and when Rick handed it back to her she began reading off the questions. "Have you held hands? Have you hugged?"

A frown formed on Kate's face. She hadn't taken that good of a look at the website when Rick had the iPad, but from first glance it wasn't one she recognized. Now the quiz was beginning to sound like something out of _Seventeen_ _Magazine_. "Who's this quiz for? Eight graders?"

"Admittedly, it starts a bit simple, but it gets more complicated."

To move the quiz along Rick answered, "Yes, we've done both of those."

"Have you kissed? Have you made-out?"

"Ah." Rick hesitated before looking to his companion.

Kate felt her cheeks flame. Oh, this was just perfect—just _perfect_ —and the exact reason why she did not want to take the quiz to begin with! She hadn't thought about that night in…well, it had been a long time and over a decade has passed since it happened. Once their hangovers had worn off they both agreed it was best never to mention their New Year's Eve midnight kissed that turned into a little bit more in an awkward-drunken sort of way. _Especially_ since they had both been seeing other people at the time.

"It was one time and we're _not_ going to talk about it." Kate said in a tone not unlike the ones she used during her interrogations at the Twelfth.

Esposito laughed at his coworker. "Okay, this is getting fun now."

"Shut up Espo."

"Guys shh!" Jenny hushed in her motherly tone. "We're getting to the important stuff now. Have you seen each other naked?"

Kate's irritation lessened immediately. A slow smile crossed her face as she vividly recalled the day while on patrol she had the privilege of watching two fellow officers pull her friend's naked ass down from a stolen police horse. Though she later had to use one of the limited favors she'd accrued during her short tenure on the force to get him out of his cell, it had been worth it a dozen times over. "I've seen him but he hasn't seen me."

"Yes I have."

Her jaw dropped. "When?"

He leaned against the arm of his seat. "Remember like three summers ago when you dove in the pool and your top came off? We all saw that," he said, gesturing towards their quartet.

 _Shit_ , she thought, blushing again. That certainly had not been one of her finer moments. Three years later she still had no idea how she was not aware of her state of undress until she stood up in the pool and Esposito had gasped out a curse. "But that only half counts there's no half option."

He hummed and shook his head. "No I've seen the other half."

Her jaw dropped and she demanded, "When!?"

"Similar incident—your suit was coming down and I, ah, saw your butt."

Kate did not take notice to the slight pink tone on her friend's cheeks. Instead, she tried to think of the moment to which he referred, but she could not. Then again, given how many times they'd been in his pool together, it certainly was possible. Still…"I don't think that counts."

"It so counts!"

"It's counting." Jenny confirmed. "Had sex?"

"No."

"Wait this includes oral." Esposito quickly added.

"Still no."

"Hand jobs?"

"Espo!"

"Guys c'mon." Rick stepped in. "The answer is no. Next question."

"Shared a bed? Cuddled? Those are yeses," Jenny said, tapping her index finger against the screen. "Honestly we can probably fill this out for them."

"Wait no," Kate jumped in. "We still have to hear what you're saying yes or no to."

With a resigned sigh, Jenny read out the list with a monotone. "Have inside jokes. Have secrets from your other friends. Gone on vacation together just the two of you."

Kate stopped their progress. "Wait we've never done that." Looking up she was met with three pairs of blinking eyes.

"You two spend the weekend out here all the time," Ryan pointed out.

"But does that count as vacation? Its property he owns…"

"Technicality," Ryan said.

"Wait!" Rick interrupted, whipping his head in the direction of his best friend. "I know—I took you to that B&B a year after your mother died."

Kate nodded; she had forgotten about that and though it was only one night, technically she supposed it did count as a vacation. Truth be told, she didn't remember much about the trip so close to the anniversary of her mother's last day on the planet except that the room smelled of roses—not real roses, but fake overly perfumed roses like those in cheap air freshener or potpourri. Otherwise, her memory was hazed with grief and the fear she was burdening her friend who she knew only booked the room out of her desperate plea to be "anywhere but here."

Shaking away the unpleasant memory, Kate cleared her throat and said, "Next question."

* * *

Richard Castle could not say he was shocked when their answers were mostly in the affirmative. They had known each other for nearly two decades—gone from teens to young adults to full adults together; of course they had many shared experiences. Some things just made sense—like them speaking together every day and spending some holidays together—but they still had a negative answer now and then: they had never lived together nor had they been out of the country together.

"Do you remember the day you met?" Jenny asked.

"I do."

Castle looked over at his companion and smiled. "Do you?"

She nodded and her grin broadened. "Yeah, I remember when my mom told me that I had to be nice to the weird little boy who was coming over with his mother."

Castle's jaw dropped and his alleged best friend let out a loud laugh. "Weird little boy! She called me a weird little boy?!" Unbelievable!

Kate laughed louder. "No, she called you a nice little boy. Weird was my assessment after you showed up wearing a cape and carrying around that notebook."

"How old were you?" Jenny asked.

"Twelve" They answered together.

"Dude. Why were you wearing a cape?" Espo asked.

Castle shifted uncomfortably in his seat. Truth be told he didn't remember the exact reason other than he was going through a superhero phase. "It doesn't matter, but I remember being afraid of her." Most of the event was fuzzy and he only strongly remembered his great annoyance at having to go with his mother to meet a lawyer when he clearly would have been fine staying in their apartment by himself. However, when he arrived and saw the scowl on young Kate's face he tucked his cape tighter on his shoulders and sat down on the floor and pretended she was an evil supervillain.

The group laughed. "I can see that," Ryan said.

Kate cleared her throat. "Yes well…it took us a couple meetings to get along but then we were-"

"Inseparable." Castle finished with a smile. Sure, they'd had drifted in and out of closeness a few times during their teen years, but their friendship had always been there underneath.

Kate's gaze dropped to her lap and she said, "Yeah, something like that."

"Have you ever made a pact about getting married?"

Castle's brow wrinkled as he looked towards the question asker. "What does that mean?"

"You know 'if we're both single at 40, we'll marry each other'…" Jenny explained.

Castle's brow rose. Oh, shit. He had almost forgotten but in that moment it all came back to him. His voice very quiet, he looked towards Kate and said, "We have, actually…"

"You're kidding!"

"When was this?"

Kate's gaze broke from Castle's and she looked at the shocked faces of their friends. "We were sixteen though I'm not sure if it was an official pact or not…"

"What were the terms?"

"That if we were both single when we turned thirty three we would marry each other and have a bunch of kids…"

As the echoes of his sentiments from sixteen years earlier filtered through his ears, Castle laughed. "I think I was kind of kidding about the "bunch" part but yeah, that was the gist of it."

Damn that had been forever ago, hadn't it? But the more he thought about it, the fresher the memory became. It had taken place at the reception of his mother's second wedding. A small affair compared to the first with only around forty guests. Not wanting to go alone, Castle had invited his best friend.

They sat together for the short-and-sweet ceremony and then again for the reception meal. Their conversation had not begun until they were sharing a piece of lemon cake for dessert. At that time, Kate was dating a guy in her grade and Rick casually asked her if she had plans to marry him. She laughed and said it was far too soon to tell, but most likely not, which sparked a conversation of their general feelings of marriage.

Castle did not remember all the details and he suspected the two glasses of champagne he'd swiped for them had something to do with it, but somehow he'd suggested that he wasn't sure if marriage was for him, but by forty he would probably be ready to settle down and that if they were both single, they should marry each other. Kate had refused, saying she wanted a child and forty would be too old. They had gone back and forth several times, but ultimately decided on thirty-three for whatever reason. To seal the deal, they'd signed a napkin. Castle doubted he thought of that pact more than one or two times since, but suddenly it was feeling very relevant.

"Would you guys like your results?"

Jenny's voice pulled Castle from his inner thoughts and he said, "Sure; why not."

"It says…'Oh my god, why aren't you married already?'"

The group fell into a twenty second period of silence that felt like an eternity. Castle couldn't say he was shocked to hear the results. If he had a dollar for every time someone had asked "Are you two a couple?" or said "You should be a couple" to he and Kate over the years he wouldn't need to write any more best sellers. When it came right down to it, he wasn't sure there was even a solid reason why other than they simply weren't and had never been. If forced to provide an explanation he would have said they met as kids and grew up as friends, but he wasn't confident in that reasoning.

Had he and Kate ever come close to becoming more than friends over the years? Castle thought so. A few times, actually. He'd even tried to muster up the courage to ask her about it a few times, but always backed down, fearful of ruining the most valuable relationship in his life because at the end of the day, his friendship with Kate was too important to be ruined—particularly not by a silly internet quiz.

As the silence expanded past the thirty second mark Castle forced out a laugh to clear the air. "Well thank god it's just a quiz."

Heat prickling at the back of his neck, he ventured a look at Kate only to see she was pulling his The Flash shirt up and over her head, an ill-looking expression on her face. In his gut he knew she was most likely teetering on the edge of being very upset. "Kate?"

"What?" she asked, a clipped edge to her tone as she stood up and brushed some sand off her knees.

"Kate, I'm sorry; I really thought it would just be funny." Jenny chimed in.

Kate shrugged. "It was funny. I'm just going to run to the bathroom; I'll be back." Without bothering to look any of them in the eye, she turned on her heel and headed back up the sand towards the main house.

Castle sighed as he picked up the discarded shirt and pulled it over his head. One thing he knew to be indisputably true about his best friend was that when it came to her emotions her response heavily favored flight over fight. Had Kate found the quiz to be an amusing anecdote, she would have chuckled, flipped over on her back and stuck her legs back out into the sun. The fact that she was scampering off with a pallid expression meant the quiz hit a bit too close to home. He'd give her ten minutes, but if she didn't come back—and he suspected she wouldn't—he'd follow; the conversation they needed to have could only be done privately.

* * *

Sitting on the edge of the pool deck, her legs dangling lazily in the water, Kate stared casually at the ripples formed from the water bouncing off the tiles. Well. That Saturday afternoon certainly had not turned out as she expected.

It wasn't Jenny's fault, per se. Kate knew she hadn't meant the quiz to be malicious and it was intended all in good fun, but the longer it went on, any amusement vanished as the questions began hitting closer and closer to home. Castle was her best friend; no question existed in her mind. But with their friendship as lengthy as it was, it overlapped quite heavily with a romantic relationship—a marriage. Hell, being that they met when they were twelve, Kate and Rick not only knew each other longer than every married couple she knew, their years together were double and triple if not longer than most couples.

Kate had never been the type of woman who defined herself by a romantic relationship or by a boyfriend. She had many relationships over her adult life, some long, some short, but she focused mostly on her career and as she had become the NYPD's youngest female detective, that focus paid off and she did not regret one moment of it. Still, now that she was over thirty, the idea of finding a husband and having a family was more prevalent in her mind.

Of course she had on occasion thought about her best friend as a potential mate, but such thoughts felt so unattainable. They were friends, pals. Save a few rare occasions there had never been anything romantic or sexual between them. But yet…he was the only person who could make her smile simply by looking at her. He was the one person she felt she was one hundred percent herself around. For nearly two decades he was the one person who consistently felt like home.

"I forgot about the marriage pact."

Startled, Kate jumped and rotated around to see the writer standing on the pool deck a few feet away. She shouldn't have been surprised that he followed her, but she was a little bit. She thought their one-on-one conversation would be later in the evening, perhaps after Kevin and Jenny put the baby to bed, but it appeared he was impatient—what else was new?

"Though to be fair," he continued, "I've blocked out a lot of Mother's weddings…"

Kate let out a light laugh as he sat beside her. "I still have the napkin we signed."

His eyes widened. "You're kidding!"

"No, I forgot about it too until a few years ago. Dad gave me a box of my high school stuff–it was in there."

He hummed but they otherwise sat in silence for almost a full minute before he began gently, "Kate."

Her heart leapt into her throat and she felt the beginning of tears in her eyes. She did not want to have this conversation. She really, really didn't. It terrified her more than she could express because if she lost him…god, if she lost him… But it was beyond her control; the conversation was coming whether she was ready or not. "This is so stupid. I want to say we're adults and whatever conversation we're about to have we can deal with and no matter the outcome we'll be fine but it doesn't feel that way. Someone's going to get hurt."

"You're my best friend," he said, his voice steady.

"And you're mine." She looked over at him and saw his brow taunt. The tightness in her chest relaxed fifteen percent; it made her feel better to see he struggled as well.

"I don't think there's a middle ground here, unfortunately. It'll either work or it'll take our friendship down with it."

"Agreed." She, unfortunately, saw no other way. Were they to embark on a romantic relationship that ended poorly she could not foresee a situation in which their friendship remained intact; there would be too much heartbreak.

He reached out and placed his hand atop hers. "I don't want to lose our friendship."

Kate sucked in a deep breath and pushed it out through her nose. "Neither do I." So that was it. They wouldn't try; they would continue on as they were. She could be all right with that—she would be all right with that.

Castle's fingers closed around her palm and he gave it a squeeze. Rotating his body towards hers, he continued. "Then…seeing as we're going to be thirty-three next year, we should probably try dating before we jump right into marriage."

Kate's jaw dropped as a smile blossomed on his face. What was he—but he just!—and now…

"That's what you want isn't it?"

"I…" Her voice trailed off and the vision she had during Jenny's quizzing: she and her best friend sitting on the beach with a little boy digging in the sand at their feet. He had brown hair, blue eyes, and a sparkling grin that melted her heart. "Yeah," she continued, her voice gravely, "I think so. I mean, I only realized it about fifteen minutes ago but…yeah. I don't know how I didn't see it. I mean, I did…but it was never right…"

"What do you mean?"

She brushed her fingertips beneath her nose and pulled her legs out of the water so her heels rested at the edge of the tile and she could wrap her arms around her shins. "The morning after my mom was killed. I woke up feeling…lost, empty, horrible. But you were there, your arm was around me and when I opened my eyes and saw your face I just thought he's here and it's going to be okay. I don't know how, but it's going to be okay."

His mouth opened but no sound came out for several seconds. "Y-You never told me that before…"

She shook her head. "I know…it sort of got lost, buried in all my grief but I remember that moment clearly and everything bad that's happened since—my dad's rehab, my car accident, when I was shot—I had the same feeling when you showed up. Rick's here; it's going to be okay."

He scooted a bit closer to her. "And you never thought to say anything."

She gave a half smile and shrugged. Looking back it seemed silly, but it truly had never crossed her mind. "It wasn't a romantic feeling, though. It was love, but friendship love. I think… all I know is you're the person I want to share everything with. Anything good or bad that happens to me you're the first call I make."

"Me too."

Reaching out his left hand, he tapped the underside of her chin with his index finger so she tilted her head up and pressed her lips against his. Though cheek kisses were more their style, kisses on the mouth happened in moments of great joy or strife. This kiss, however, was different than all the others as it, for the first time, opened the door to more.

When their lips broke, Kate moved her arms from around her legs to around his neck. She pulled herself closer to him and nudged their foreheads together. Eyes still closed she asked softly, "Are you sure you want this?"

He hummed and stroked his hands over her forearms. Leaning back, he gazed down at her when she opened her eyes. "You know me—serial monogamist. Never thought I was the marrying kind, but when I think about the future, when I think about forever…" He shook his head once and spoke with conviction. "The only face I see is yours."

Kate's heart lifted and her chest constricted for an entirely different reason than before; she felt the same. With a happy laugh, she brought their lips together that more, that time kissing him like she never had before. He skimmed his hands up and down her spine until the tingles had her breaking their kiss with a happy laugh.

"Mmm okay." He spoke gruffly. "Why _aren't_ we married already?"

Judging by his tone he had enjoyed their kiss as much as she had. The thought of all the firsts they were about to encounter had her tugging at her bottom lip with her teeth. Damn it was going to be quite a ride, wasn't it? She kissed him quickly and answered simply. "It just wasn't our time yet."

"But now it is?"

"Yeah," she nodded, "it is."

* * *

 _Thank you for reading!_


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